Getting A number on a user phone when doing a Call Pickup

I notice that Call Pickup (General Call pickup (*8, defined in features.conf) or Directed Call Pickup (implemented in Asterisk dialplan by using Pickup() application)) is a feature that is quite commonly used by phone system users. The features is working OK with Asterisk, what I am seeing is a problem with displaying the A number on the phone of the user that initiates the call pickup.


A calls B
C does General Call Pickup (*8) and picks up a call from B

The problem that I see is, that on the C phone, the number *8 is displayed (the number that the user dialed to pick up the call that was ringing at B). But what I would like to see is, that the number that is displayed on C phone is the A number. That is how some legacy system work and to be honest, I think this is a very nice feature to have.

I am interested in using only SIP phones. Does anyone know of a phone vendor that supports this? Is there a setting in Asterisk that controls the Asterisk support for this?

In case you didnt find answer and if you are using asterisk 1.8, in sip conf just uncomment
this lines:
trustrpid = no ; If Remote-Party-ID should be trusted
sendrpid = yes ; If Remote-Party-ID should be sent (defaults to no)
sendrpid = pai ; Use the “P-Asserted-Identity” header

and that it, it should work with all phones.

“sendrpid = pai” works perfect with Aastra phones. Did not try much other vendors, but it should work on any IP phone that supports reading information from “P-Asserted-Identity” header.